Conventionally, each of a pair of handcuffs comprises two rectangular base bodies which accommodate frame plates, a partition plate between the frame plates, a pair of pawl pieces and a leaf spring therein; a movable arm formed in a semi-circle shape, which is provided at its free end with a ratchet portion formed with dual line of teeth; and a pair of fixed arms formed in a semi-circle shape, which are pivotably connected at free ends thereof to the other end of the movable arm by a pivot pin and are integrally provided at their other ends with the rectangular base bodies, wherein the dual line of teeth in the movable arm are movably engaged with the pawl pieces of the base bodies. The base bodies of the handcuffs are connected each other by chains or rings.
Further, it has been known that the base bodies are connected each other by a hinge instead of the connecting chains or rings. One hinge member has its one end fixed on the base body of the handcuff and has the other end thereof connected to one end of the other hinge member by a hinge pin, so that a pair of handcuffs can be foldable on each other.
In case of the above handcuffs, one end of the hinge member fixed on the base body of the handcuff has to be formed flat, while the other end of the hinge member connected to the other hinge member has to be formed in a hinge shape. In this regard, however, in order to prevent the handcuffs from being easily picked or disassembled, there should be no gap between the flat part and the hinge part of the hinge members, and particularly a hinge opening should be integrally formed in each of the hinge member. For this reason, for the integral formation of the hinge openings, the flat parts and the hinge parts must be formed by cast-iron method.
Accordingly, due to the cast-iron formation, the weight of the handcuffs becomes increased and it is inconvenient to carry along the handcuffs. Also, the productivity and workability of the handcuffs are remarkably deteriorated due to the cast-iron formation method, and thus the manufacturing cost of the handcuffs is increased.